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Insights into Functional-Group-Tolerant Polymerization Catalysis with Phosphine–Sulfonamide Palladium(II) Complexes

Insights into Functional-Group-Tolerant Polymerization Catalysis with Phosphine–Sulfonamide Palladium(II) Complexes

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JIAN, Zhongbao, Laura FALIVENE, Philipp WUCHER, Philipp ROESLE, Lucia CAPORASO, Luigi CAVALLO, Inigo GÖTTKER-SCHNETMANN, Stefan MECKING, 2015. Insights into Functional-Group-Tolerant Polymerization Catalysis with Phosphine–Sulfonamide Palladium(II) Complexes. In: Chemistry - A European Journal. 21(5), pp. 2062-2075. ISSN 0947-6539. eISSN 1521-3765

@article{Jian2015Insig-29489, title={Insights into Functional-Group-Tolerant Polymerization Catalysis with Phosphine–Sulfonamide Palladium(II) Complexes}, year={2015}, doi={10.1002/chem.201404856}, number={5}, volume={21}, issn={0947-6539}, journal={Chemistry - A European Journal}, pages={2062--2075}, author={Jian, Zhongbao and Falivene, Laura and Wucher, Philipp and Roesle, Philipp and Caporaso, Lucia and Cavallo, Luigi and Göttker-Schnetmann, Inigo and Mecking, Stefan} }

Falivene, Laura Mecking, Stefan Göttker-Schnetmann, Inigo Roesle, Philipp Roesle, Philipp Two series of cationic palladium(II) methyl complexes {[(2-MeOC<sub>6</sub>H<sub>4</sub>)<sub>2</sub>PC<sub>6</sub>H<sub>4</sub>SO<sub>2</sub>NHC<sub>6</sub>H<sub>3</sub>(2,6-R<sup>1</sup>,R<sup>2</sup>)]PdMe}<sub>2</sub>[A]<sub>2</sub> (<sup>X</sup>1<sup>+</sup>-A: R<sup>1</sup>=R<sup>2</sup>=H: <sup>H</sup>1<sup>+</sup>-A; R<sup>1</sup>=R<sup>2</sup>=CH(CH<sub>3</sub>)<sub>2</sub>: <sup>DIPP</sup>1<sup>+</sup>-A; R<sup>1</sup>=H, R<sup>2</sup>=CF<sub>3</sub>: <sup>CF3</sup>1<sup>+</sup>-A; A=BF<sub>4</sub> or SbF<sub>6</sub>) and neutral palladium(II) methyl complexes {[(2-MeOC<sub>6</sub>H<sub>4</sub>)<sub>2</sub>PC<sub>6</sub>H<sub>4</sub>SO<sub>2</sub>NC<sub>6</sub>H<sub>3</sub>(2,6-R<sup>1</sup>,R<sup>2</sup>)]PdMe(L)} (<sup>X</sup>1-acetone: L=acetone; <sup>X</sup>1-dmso: L=dimethyl sulfoxide; <sup>X</sup>1-pyr: L=pyridine) chelated by a phosphine–sulfonamide were synthesized and fully characterized. Stoichiometric insertion of methyl acrylate (MA) into all complexes revealed that a 2,1 regiochemistry dominates in the first insertion of MA. Subsequently, for the cationic complexes<sup> X</sup>1<sup>+</sup>-A, β-H elimination from the 2,1-insertion product <sup>X</sup>2<sup>+</sup>-A<sub>MA-2,1</sub> is overwhelmingly favored over a second MA insertion to yield two major products <sup>X</sup>4<sup>+</sup>-A<sub>MA-1,2</sub> and <sup>X</sup>5<sup>+</sup>-A<sub>MA</sub>. By contrast, for the weakly coordinated neutral complexes<sup> X</sup>1-acetone and <sup>X</sup>1-dmso, a second MA insertion of the 2,1-insertion product <sup>X</sup>2<sub>MA-2,1 </sub>is faster than β-H elimination and gives <sup>X</sup>3<sub>MA</sub> as major products. For the strongly coordinated neutral complexes <sup>X</sup>1-pyr, no second MA insertion and no β-H elimination (except for <sup>DIPP2</sup>-pyr<sub>MA-2,1</sub>) were observed for the 2,1-insertion product <sup>X</sup>2-pyr<sub>MA-2,1</sub>. The cationic complexes <sup>X</sup>1<sup>+</sup>-A exhibited high catalytic activities for ethylene dimerization, affording butenes (C<sub>4</sub>) with a high selectivity of up to 97.7 % (1-butene: 99.3 %). Differences in activities and selectivities suggest that the phosphine–sulfonamide ligands remain coordinated to the metal center in a bidentate fashion in the catalytically active species. By comparison, the neutral complexes <sup>X</sup>1-acetone, <sup>X</sup>1-dmso, and<sup> X</sup>1-pyr showed very low activity towards ethylene to give traces of oligomers. DFT analyses taking into account the two possible coordination modes (O or N) of the sulfonamide ligand for the cationic system <sup>CF3</sup>1<sup>+</sup> suggested that the experimentally observed high activity in ethylene dimerization is the result of a facile first ethylene insertion into the O-coordinated PdMe isomer and a subsequent favored β-H elimination from the N-coordinated isomer formed by isomerization of the insertion product. Steric hindrance by the N-aryl substituent in the neutral systems <sup>CF3</sup>1 and <sup>H</sup>1 appears to contribute significantly to a higher barrier of insertion, which accounts for the experimentally observed low activity towards ethylene oligomerization. Cavallo, Luigi Jian, Zhongbao Göttker-Schnetmann, Inigo Wucher, Philipp Caporaso, Lucia Insights into Functional-Group-Tolerant Polymerization Catalysis with Phosphine–Sulfonamide Palladium(II) Complexes 2015-01-12T09:28:18Z Falivene, Laura 2015-01-12T09:28:18Z Wucher, Philipp Caporaso, Lucia Mecking, Stefan Cavallo, Luigi eng 2015 Jian, Zhongbao

Dateiabrufe seit 12.01.2015 (Informationen über die Zugriffsstatistik)

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